This invention relates to mechanisms for aligning a transmission indicator and indicia, and more particularly to mechanisms which permit adjustment between the indicator and indicia after assembly.
As a general rule, automatic transmission indicator mechanisms are urged by spring load to move in one direction; i.e., toward Park position, and movable by a manual lever in the opposite direction against the spring force.
The indicator mechanism usually has five or more positions, such as Park, Reverse, Neutral, Drive and Low, which display to the operator the tranmission operating condition that has been selected by the operator with the manual lever. An indicator pointer is moved to align with respective indicia for each operating condition as selected when the manual lever is moved.
It is desirable to provide a mechanism which will permit alignment or "zeroing" between the pointer and indicia after assembly in the vehicle. There have been many mechanisms proposed to accomplish this function automatically. These have included friction connections and ratcheting connections between the manual lever and pointer. Both of these types of systems require a stop member or surface to be located, with a degree of accuracy, relative to one or both ends of travel of the pointer. With these mechanisms, the pointer is stopped when aligned with indicia at one end of travel, while the lost motion connection permits continued travel of the manual lever, which is connected with a transmission selector valve, until the respective transmission condition is selected. When the current operating condition in the transmission is reached, the manual lever is prevented by the transmission valve selector from further movement. At this point, the indicator and indicia are properly aligned. This alignment can only be accomplished at the extreme ends of selector travel, usually Park or Low.
There are other systems of adjustment which permit the connection between the manual lever and the indicator to be released during adjustment. These systems permit the indicator pointer to be moved by an operator independently of the manual lever until proper alignment is achieved. At this point, the operator must exert sufficient force to maintain the alignment and simultaneously reconnecting the indicator pointer and the manual lever. This generally means that the operator is required to hold the indicator pointer against the force of the return spring while tightening a threaded fastener such as a bolt. The operator must use both hands and at least one tool in a limited space adjacent the steering column to perform this function. Thus, there is a degree of difficulty in making this adjustment and the operation can be time consuming.